Table concentrator



A. H. STEBBINS TABLE CONCENTRATOR 1 July 16, 1929.

Filed June 3, 1927 4 Sheets-Sheet 1 ATTORNEY July 16, 1929. $TEBB|N5 1.720.862

TABLE CONCENTRATOR Filed June 3, 1927 4 Sheets-Sheet 2 /NVENTOR.'

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ATTORNEY July 16, 1929.

A. H. STEBBINS TABLE CONCENTRATOR Filed June 3, 1927 4 Sheets-Shet 3 64' 50 O O O O 46 h 2* Wflfi%% & g \m 80 /NVNTORX BY ATTORNEY July 16, 1929. I A. STEBB |NS 1.720.862

TABLE CONCENTRATOR Filed June 5, 1927 4 Sheets-Sheet 4 I Fl I 1 a FM. 2 9 -3 a 05; O O o o J b k A 7 la; l

Patented July 16, 1929.

hearse starts ALBERT H. STEBBINS, OF LOS ANGELJ ES, CALIFORNIA.

TABLE eoncnn'rnn'ron.

Application filed .Time 3, 1927. SeriatNo. 196,367.

This invention relates to novel features in the construction of concentrator decks, and also to novel form of movement imparted to the deck.

Dry table concentrators as usually constructed are provided with a deck having a deck surface that is supported at: a transverse inclination and over which riflles extend di-.

agonally to direct the concentrates towardthe upper side of'the deck. v

It found that the concentrates from which the major portion of the tailings have been removed travel more freely along the channels between the ri'tl'les than the unsep'arated material lying nearthe material receiving end of the deck. It is therefore feasible to impart a greater transverse inclination to the portion of the deck lying near itsdischarge end than can be given the portion of the deck lying near the feed hopper.

One important feature of the present in-- vention therefore resides in a concentrator deck having a deck surface that is supported at a transverse inclination and the pitch of which gradually increases from the material receiving end of the deck toward the discharge end thereof. As a result of the gradual change in the inclination of the deck surface, each portion of the deck surface is given the particular transverse inclination that is best suited for the condition of the materials being treated upon that portion of the de k. The increase in the transverse inclination of the deck toward the discharge end thereof also helps to work the tailings outof the concentrates and down the deck surface toward the lower side thereof, andpermits the use of steeply inclined ritlles. 1

In the dry concentrator decks as commonly constructed heretofore the transverse inclination of the deck surface einployedto promote the flow of the tailings toward the lower side of the deck has been too steep totreat the concentrates lying nearthe concentrate wall tothe best advantage. That as the" con centrates travel along the concentrate wall thcyare subjected to a final or high grading treatment. which ininany cases can bebetter perforn'ied on a relatively flat surface. Another feature of the present inventiontherefore resides in a concentrator deck having the marginal portion of the deck surface lying adjacent the concentrate wall disposed at a less transverse inclination than the rest of the deck surface.

Still, another feature of the present invenof deck;

tion resides in operating means for adeck whereby an up-throw or vibrator I movement is imparted to the deck in a; direction to shift the materials slightly toward the material receiving end of the deck the moven'ient being suchthat it serves to work the concentrates away from the rifiies against which they pile up and tend to overflow. i

Other features of the invention and novel combination of parts in addition to the above will be hereinafter described in connection with the accompanying drawings which illustrate good practical forms of the invention.

In the drawings,- v i Fig. l is a side elevation, with parts in Sec tion of a table concentrator construction in accordance with the present invention Fig. 2 is a top plan view of a twin deck such as shown in Fig. 1,.the hood extending over the deck being omitted; A F ig. 3 on. an enlarged scale is a sectional View taken on theline 3'3 of Fig. 1; ig. at is atop plan view of the supporting frame for the deck and of means for'imparting a vibratory movement to'the deck; the deck and its supporting carriage being omitted; f

Fig. 5011 an enlarged scale is a sectional view taken on the line 5'5 of Fig. Q the deck surfacebeingomitted in order to show the construction of the deck frame for supporting the deck surface at agradually increasing transverseinclination. i Fig: 6 on an enlarged scale is aside view of a portion of the deck supportingframe of Fig.1; f

Fig. T is". a side elevation of a portion of the deck carriage and shows the supporting arms imparting an upthrow movement to the deck;

Fig. 8'is a top plan view of a modified type Fig. His a sectional view taken on the line F1 10 is a vertical sectional'view throu h 2: a portion ofthe deck of Big. 2 and shows means for removing the concentrates from the deck surface Fig. 11 on an enlarged s'caleis a top plan view of portion of theconcentrate wall showing the same provided with diiferent types of deflectors;

' Fig. 12 is a side view of the parts shown in Fig. 11:

Fig. 13 is aftop plan viewof the material receiving end portion of thedcck showing I a modified arrangement of the feed hoppers;

Fig. let is a transverse sectional view through a twin deck provided with a modified type of riflies, and

Fig. 15 is a sectional perspective View taken on the line 1515 of Fig. 13.

A number of the features of the present invention may be embodied in a twin deck construction such as shown in Figs. 1, 2, 3 and 5; or in a single deck such as shown in Figs. 8 and 9.

Referring first to the twin deck type of concentrator, the same is provided with the oppositely inclined deck surfaces 10 which are supported so that they slope downwardly from the ridge or central portion 11 of the deck surface. The deck frame is preferably so constructed that an air chamber 12 is formed beneath the deck surfaces in .order that air may be forced into the air chamber and upwardly through apertures 13 formed throughout the entire deck surface, or any desired portion thereof. The materials to be treated may be fed to the oppositely inclined deck surfaceslO by the feed hoppers 1 1 which hoppers, it will be noted, are shown as extending practically entirely across the end of each deck surface to the lower edge thereof, the arrangementbeing such that the materials will be delivered to substantially the entire end portion of each deck surface by the fed hoppers 14.

As above pointed out, an important feature of the present invention resides in the construction of the deck whereby the transverse inclination of the deck surfaces 10 is gradually increased from the feed end of the deck towards the discharge end thereof. In order to support the deck surfaces in this manner the deck frame is shown as pro vided with a large number of transversely extending beams 15 which slope upwardly from the opposite sides 16 of the deck frame towards the central ridge 11, and it will be noted from Fig. 5 that the inclination of these beams 15 is gradually increased from adjacent the feed end of the deck towards the discharge end thereof; that is, the beams 15 lying near the feed hoppers 14 are shown as having a relatively slight inclination, whereas the beams 15 lying near the discharge end of the deck are shown as having a much steeper inclination. As above indicated a further feature of the invention 'resides in the construction whereby'that portion of the deck surface lying near the concentrate wall is given a flattened construction. This is produced by reducing the inclination of the beams 15 near their inner ends, as clearly indicated by 17'of Fig. 5. By forming the supporting structure for the deck surface in the manner just described the desired transverse inclination may be imparted to each portion of the deck surface. The deck surface 10 may be COIlVGlliently formed of flexible metal strips 18 that are trough-shaped in cross-section, as shown in Fig. 8 and which have the up-turned side portions adapted to form the ritiles 19 as more fully shown in Fig. 7 of my Patent Numbered 1,505,734, granted August 11 1924. These trough-shaped strips 18 are secured diagonally across the deck surface as shown in Fig. 2, and are sufliciently flexible to readily conform to the gradual increase in inclination of the deck supporting beams 15. The air apertures 13 above mentioned may be formed in the riftle forming channels 18.

As the materials travel lengthwise of the deck the concentrates which work down under the tailings will be be directed towards the upper side of the deck by the riflles 19, while the tailings will flow laterally over the riffles towards the lower side of the deck in a well known manner. This separation or stratification of the materials is promoted by the air passing upwardly through the apertures 13 and also by the vibratory movement which is imparted to the deck in a manner to be described. The concentrates upon reaching the ridge or flattened portion 11 of the deck may be caused to travel along a zigzag path such as indicated in Fig. 2 near the material receiving end of the deck, or may be otherwise treated to subject them to a final or high-grade treatment. In or der to couse the materials to travel over the Zigzag path just mentioned, certain of the riflles 19 are extended beyond the other riffles, as indicated by 20, so that they will serve to deflect the concentrates from one side of the ridge 11 to the other, as will be apparent from Fig. 2. This will help to work the remaining tailings out of the concentrates and to direct these tailings down the oppositely inclined deck surfaces 10.

After the concentrates have traveled some distance along the flattened portion 11 of the deck they may be subjected to the action of the deflectors 21 which may be given various different constructions best shown in Figs. 11 and 1.2. These deflectors may be secured in the desired position of adjustment to the concentrate or upstanding wall 22 extending lengthwise of the deck. The deflectors 21 are inexpensive to construct and may be easily secured to the wall 22 in any desired position lengthwise of the deck by the clan'ipingbolts 23. The construction of the deflectors 21 is such that they force the concentrates traveling along the ridge 11 away from the concentrate wall 22 and this serves to crowd the tailings off the flattened surface 11. The deflectors 21 may extend only a short distance from the concentrate wall as shown at the righthand side of Fig. 11 of the drawing. or if desired these deflectors may be provided adjacent their ends with the raised portion 21 adapted to form a skimmer under which the concentrates may pass while the tailingslying above the concentrates will be forced down. the inclined sides of the deck. If desired the deflectors 21 may be given the construction shown at the left-h and side of Fig. 12, wherein it will be seen that the scraper 24 is supported by the side plates 25 for vertical adjustment towards and from the deck surface 11 to thereby vary the size ofthe opening below the scraper 23 under which'the concentrates may pass.

It may be desirable to remove the concentrates from the deck surface at different points lengthwise of the deck and this may be conveniently done by providing the openings 26 in the ridge portionll of the deck surface, as will be apparent from Fig. 2. Means may be provided for opening and closing the different discharge apertures 26 to thereby regulate the degree of retreatment to which the concentrates are subjected before they'are per-- mittedto' escape from the deck. lVhile the openings 26 may be formed of various types of gates or closures, one good construction to this end is shown in Fig. 10 wherein it will be seen that each concentrate discharge opening 26 is formed in a plate 27 which may be set in a portion of the deck surface and se cured thereto by bolts 28. Each plate 27 may be provided with a downwardly extending lug 29 to which a rocl'iing'lever 30 may be pivotally secured by a pin 31. One end of the lever 30 is provided with a head 32 adapted to close the opening 26 and the opposite end of the lever 30 is connected to the'rod 33 having a hand operated nut 3 1 at its upper end and which is adapted to pull the rod upwardlyto hold the opposite end 32 of the leverout of its apertured closing position, as will be apparent from the drawing. A spring 35 may be provided to normally hold the leve113O in its aperturcd closing position as shown. The air which is confined inthe space 12 below the deck surface should be excluded from the discharge openings 23 and the closure means ust described. The closure mechanism for each opening 26 is therefore positioned in a chamber formed below'the deck surface and] from which air under pressure 'is excluded by the surrounding walls 36, andthe concentrates which, escape from any one of the openings 26 may fall into a conveyor trough37 which may be attached to 'tlie lower wall 38 of'the concentrator deck.

The concentrator deck of Fig. 2 is prefer ably provided with an upstanding wall 39st each side thereof and which extends a siibstantial distance along the lower side of each deck surfacelO. These upstanding walls 39 serve to retain a bank of the tailings lying along the lower sides of the deck surfaces 10 upon the deck surface to subject them to a panning action which will cause such concentrates as may remaln in these tallings to 'worlcdown the direction of their length andare arranged.

to decrease the width ofth'e deck surface to ward its discharge end.

The concentrates which reach the discharge end of the flattened portion 11 of the deck may enter a hopper 411 and the iniddlings which reach the discharge end of the deck may enter the hoppers 12. The concentrates which pass dowm ardly through. the openings 26 into the trough 37 and those which pass through the'discharge openings 26 disposed near the discharge end of the deck are directed into the concentratereceiving receptacle 43, as will be apparent'fron'i Fig. 1. i

a result of the deck construction so far described it will be seen that as thematerials travel lengthwise of the deck the concentrates will travel along the riflles 19 towards the concentrate wall 22 while the tailings which flow overthe ritlies will work down the inclined deck surfaces towardstheretaining walls 39, and. as the separation of the materials progresses the transverse inclination of the deck is gradually increased; this will help to crowd the ta-ilings out of the channels between the riflles and to workthem towards the lower side of the deck; Asa result of this construction each portion of the deck is given a transverse inclination which is best adapted to accommodate'the type of materials being treated upon that particular portion of the deck. The transversely iiiclined riflles 19 are preferably given the tapered construction best shown in Fig. 3 wherein it will'be seen that these riflies are taller near the tailing retaining wall 39 than 1 theyare near the concentrate wall, this construction being desirable 111 order that the tailings which tendto'stratify above the concentrates may more readilyflow over the riflies as tl'ieyapproach the concentrate wall. I As aboveindicated, afurther feature of the present inventionresidcs in deck operating means whereby an upthrow or vibratory movement is impartedto the deck in such a manner that the concentrates are shifted slightly towards the feed hoppers 14 inorder to work them awayfrom the riflles over which they tendto flow. I VVhi'le various forms of movements may be employed to produce this desired effect, one good constructiontothis end will now be described.

Incarrying out this feature ofthe invention movement of the materials lengthwise of the deck towards the discharge end thereof is effected by supporting the deck at a pro nounced,inclinatiomas best showniirFig. 1, wherein it will be seen that thedeck supporting frame ismuch taller at the hopper end of the deck than it is at the discharge end there of, this frame being provided with the relatively short uprights 44 at the righthand end thereof and the longer uprights 45 at the lefthand end thereof, and to these uprights are secured the longitudinally extending beams 46. In order to accommodate different materials it may be desirable to vary the longitudinal inclination of the deck and to this end in the construction shown the deck supporting frame just described is mounted for rocking movement about the axis of a power shaft 47 to be more fully described. The central portion of the deck supporting frame is simportcd by a fixed transversely extending b uun 48 having the upwardly extending lugs 49 at the upper ends of which are provided saddles or bearing surfaces adapted to receive the outer convexed surfaces of the bearing plates 50, which bearing plates are rigidly secured to the braces 46 of the frame. The arrangement is such that as one end of the deck supporting frame is raised or lowered the entire frame will swing about the axis of the power shaft 47, it bcingsupported for this swinging moven'ient by the bearing brackets 49 the outer concaved surfaces of which. are concentric with the axis of the shaft 47. hen the supporting frame has'been tilted to the desired position it may be firmly supported in such position by the use of blocks 51 which are placed between the lower beams 46 and the floor 52 of the building, and the frame may be clamped in this position by the clamping bolts provided at the opposite ends of the concentrator.

One good. form of means for vibrating the deck in such a manner that the concentrates will be worked away from the rifHes over which they tend to flow consists in supporting the deck so that an upthrow movement is imparted to the same asit is movedba ck and forth with a vibratory effect, and to this end in the construction shown the deck is supported by the swinging arms 54 the upper ends of which are provided with stub shafts that are journaled in bearing brackets 56 secured to the upper beams 46of the supporting frame. T he lower ends of the arms 54are provided with the stub shafts 5: which are journaled in bearing brackets 58 secured to the under face of 'a. carriage ,59 upon which the deck is mounted.

The means shown for imparting aback and forth or vibratory movement to the deck consists of the power shaft 47 above mentioned andv which is rotatably mounted in the bearin g brackets 60, and this shaft is provided with an eccentric portion 61 upon which a relatively long drum 62 is rotatably mounted, the anti-friction bearing- 63 being provided between the drum and the eccentric upon which it is mounted. The deck which is supported for swinging movement in the direction of its length by the arm 54 is held against moving in the direction in which it slopes by a plurality of cables (34 which are clamped or otherwise secured to the under face of the carriage 59. These cables are looped about the upper grooved sheave 35 rotatably supported by the shaft 66. The cables 64 pass from the sheave (35 about the grooveddrum G2 and the ends of these cables extend from the under side of the drum 6'2 to the springs (37, the arrangement being such. that the compressed springs 67 exert a continuous pull upon the cable 64 to hold the deck in approximately the position in which it is shown in Fig. 1. As the eccentric shaft 4'7 is rotated by its driving pulley 47 the drum (52 will be moved through an orbital path and this will tend to slack off and tension the cable 64 to il'npart. a slight movement to the deck in. the direction of its length. The deck is positively pulled in a right-hand direction viewing Fig. 1 by the power operated cable 68 a portion of which is secured to the carriage 59 by a clamp 69. An intermediate portion. of the cable (38 is looped about a grooved sheave 7O supported by the shaft 71 and this cable extends from the under side of the sheave about a groove formed in the drum 62 and the lower end of this cable extending from the drum 62 is anchored to the frame as at 72. As a result of the construction just described, rotation of the eccentric shaft 47 serves to alternately tension and slack off the cables 64 and 68, with the result that the deck is moved back and forth with a vibratory movement, it being understood that as the power cable 68 is tensioned the spring actuated cables 64. are slacked off and vice versa as the cables 64 are tensioned, the cable 68 is slacked oif.

In order to impart the desired upthrow movement to the deck the major portion of the are through which the arms 54 swing lies to the left-hand side of the vertical line aa (sec 7) the arrangement being such that the arms 54 will move back and forth from the I position in which they are shown in full lines in Fig. 7, to the position in which they are indicated in dotted lines in this figure. The upthrow movement imparted to the materials by the construction just described will act more energetically on the concentrates lying close to the decksurface than it will upon the tailings which are separated from the deck surface by the concentrates. and as a result the concentrates will be shifted away from theritfles to a greater extent than the tailin As a result the tailings will flow laterally over the rifiies. whereas the tendency of the concentrates to do so will be'reduced and the vibratory movement imparted to the deck will tend to spread the concentrates out between thespaced riflies. The operating mechanism just described serves in a very satisfactory manner to prevent the concentrates from escaping over the sides of the .ritlies provided .as shown in Fig. 15, depending upon which ft. d hopper the movement imparted to the deck is carefully adjusted to produce the desired effect.

The air which is forced upwardly through the apertures 13 in the deck surface may be delivered to the air chamber 12 byafan 73 which is connected to the air chamber by a pipe 74. A hood 75 is preferably provided over a major portion of the deck surface, as will be apparent from Fig. 1, and air may be exhausted from beneath this hood by a pipe 76 leading to any desired form of exhaust means. i

In the modified construction shown in Figs. 8 and 9 a single deck has been illustrated in place of the twin deck above described. In this deck, as in the twin deck, the deck surface 77 is supported at a transverse inclination the pitch of which gradually increases from the material receiving end of the deck towards the discharge end thereof, the deck surface being supported at the desired inclination by a number of transversely extending beams 78 similar to the beams 15 above described. The concentrate wall 79 shown in this modified construction slopes downwardly towards the lower side 80 of the declg'and the concentrate wall is provided with the deflectorsfll which may be similar to those above described) The materials to be treated aresupplied to'this deck by the hopper 8]., and the retaining wall 82 like the retaining wall 39 abo vedescribed, is provided along the'lower side of the deck. This single deck may alsobe provided with. a relatively marginal'portion '83 which lies adjacent the concentrate wall and upon which the concentrates are subjected tothe finalor high-grade treatment similar to the action to which they are subjected while resting upon the relatively flat surfacel li above described.

In some cases it maybe desirable. to feed coarse materials onto one portion of the deck surface and finer materials onto other portions thereof, andmeans tothisend is'sliown in the modified construction of'Fig. 13, wll'ierein the feed hoppers 84 are provided to deliver the materials onto the oppositely inclined deck surfaces 10, and the intermediate hopper 85 is provided to deliver materials'onto the ridge portion 11 of the deck. Thematerials supplied by the hopper 85 may be either coarser or liner than the materials in the hoppersSt. and the coarser materials when delivered to the deck should be subjected to stronger air currents than the finer materials. This may be accomplished by increasing the size of the air apertures 18 provided near the feed hoppersSe, or near the feed hopper 85 feed hopper contains the'coai'ser materials. The increase in air force may also be produced by forming aseparate airchaniber under the portion of the deck lying in front of the trooper containing thecoarse materials, and the aortion of d r-surfac 'iaeentthe tavia f the air chamber 86 formed below the deck and into which air underincreased pressure may be forcech The increase in air strength of a smalljarea of the deck will serve' to quickly stratify the heavier materials after which they may become mixed with the finer materials treated upon the deck and be subjected through the action of the rifiles 19 and deflectors 21 to the separating operations above described. i

In concentrating certain materials it may be desirable to provide the deck surface 10 with themodified type of riflles shown in Fig. 14 wherein it will benotedthat the riflles 87 lean toward the concentrate wall. This, arirangement of the rifiies causes them to lean or extend over the concentrates traveling along the riflies and helps to prevent the concentrates from escaping therefrom. The leaning type of rililes are particularly desirable in treating ores which contain a small percentage of values, such forexample as ores containing free gold in which casethe fine particles of gold willaccumulate undertlie leaning riflles and will be prevented by this with" the tailings.

WVliat is claimed is 11A concentrator deck, comprisinga deck frame having a material supporting deck. surface, means bullt intothe deckframe" for supporting thedeck surface at a transverse inclination the pitch of whicl'i is gradually'increased from the mater al receiving end of thedeck to the material discharge end, and

rifiles arranged diagonally across the deck surface so that each rifiie extends from the lower to the upperside of the deck to direct the concentrates up the transversely inclined deck surface.

2; concentrator deck, comprising.afdeck frame having a material supporting deck surface, means for, supporting the. deck surfaceat a transverse inclination the pitch of which gradually increases from the material receiving end. of the. deck towardthe discharge end thereof, and rifil'es extending diagonally across the decksurfac'e from the lower to the. upper side of the deck'and adapted wan-ea the concentrates towards 90 construction from escaping over the rifiles the upper side of the deck along paths that T are steeper nearthe dischargeend of thedeck than theya-re near the material receiving end of the deck. a v

3 A concentrator deck, comprising a deck frame provided, witha series of downwardly inclined beams arranged transversely of the deck and having their pitch: graduallyv increased froin the material"receiving end of the deck 'toward the dischargeend thereof, a

materialsupporting}surface mounted upon said beams-and supportedthereby at a transverse inclii'iationtlie pitch of which increases from a a ottlie'deck oward-t e other,

' 1 at ting diagonally a.

as they deck surface from the lower to the upper side of the deck.

A. A concentrator deck, comprising a deck frame having a deck surface that is supported at a. transverse inclination, said deck surface being provided with a marginal portion extending along its upper side and which is disposed at a less transverse inclination to support and retreat the concentrates, rii'ilcs extending diagonally over the deck surface to direct the concentrates up the transversely inclined deck surface onto said marginal portion, and deflectors arranged along said marginal portion in spaced relation to the deck surface to arrest the upper but not the lower strata of materials traveling along the marginal portion.

5. A concentrator deck, comprising a deck frame having a deck surface that is supported at a transverse inclination and provided with a relatively flat, marginal portion extending along its upper side and which is disposed at a less transverse inclination to support and retreat the concentrates as they travel lengthwise of said marginal portion, rifl'les extending diagonally across the deck surface, and deflectors upon said marginal portion and arranged transversely of the ritlies to return the lighter materials to the ritiles.

6. A concentrator deck, comprising a deck frame having a material supporting deck surface, means for supporting the deck surface at a transverse inclination the pitch; of which gradually increases from one end of the deck toward the other, said deck surface being provided with a flattened marginal portion extending along its upper side and which is disposed at a reduced transverse inclination to support and retreat the concentrates, and riltles extending diagonally across the deck to direct the concentrates onto said marginal portion.

7. A concentrator deck, comprising a deck frame having a material supporting deck surface that is supported at a transverse inclination, said deck surface being provided with a relatively flat marginal portion ex tending along the upper side of the deck at a less transverse inclination to receive and retreat the concentrates, and deflectors positioned along said marginal portion in spaced relation to the deck surface so that the values may pass under the deflectors while the lighter materials are directed by the deflectors off of said marginal portion.

8. A concentrator deck, comprising a deck frame having a material supporting deck surface that is supported at a transverse inclination, said deck surface being provided with a relatively flat marginal portion extendmg along the upper side of the deck at a reduced transverse inclination, riflies extending diagonally over the deck surface .to direct the concentrates onto said marginal portion, and deflectors positioned along said marginal portion and arranged transversely of the riffles to return the tailings that separate out upon said marginal portion to the riilles.

9. A concentrator deck, comprising a deck frame having a material supporting deck surface that is supported at a transverse inclination and the pitch of which gradually increases from the material receiving end of the deck to the material discharge end, a concentrate wall extending along the upper side of the deck, rifiies extending diagonally across the deck from the lower to the upper side thereof and arranged to direct the concentrates against said concentrate wall, and a material sustaining wall extending a substantial distance along the lower side of the deck to support a bank of the tailings to subject them to a panning act-ion.

10. A concentrator deck, comprising a deck frame having a material supporting deck surface that is supported at a transverse inclination, a concentrate wall extending along the upper side of the deck, riftlcs extending diagonally over the deck surface to direct the concentrates against the concentrate wall, deflecters arranged along the concentrate wall to promote retreatment of the concentrates by deflecting the lighter materials back towards the riftles, and adjustable means for securing the deflectors in different positions of adj ustment along the concentrate wall. 1

11. A concentrator deck, comprising a deck frame provided with a pairof oppositely inclined deck surfaces arranged to slope downwardly from a central ridge to form a twin deck construction, the, central ridge being formed with an approximately flat surface that extendslengthwise of the deck between the oppositely inclined deck surfaces, riflles extending diagonally over the deck surfaces to direct the concentrates onto said ridge for further treatment, and deflectors arranged along said ridge in spaced relation to the deck surface to clear the values while they engage and deflect the tailings from the ridge.

12. A concentrator deck, comprising a deck frame having a twin deck construction and provided with a large number of beams arranged transversely of the deck to slope downwardly from the opposite sides of a central ridge toward each side of the deck, the beams being arranged so that their pitch gradually increases from the material receiving end of the deck toward the discharge end thereof, a material supporting surface mounted upon the beams at each side of said central ridge and supported by the beams at a transverse inclination that increases in pitch from one end of the deck toward the other, and riilles arranged diagonally across the deck to extend from the lower to the upper side of each deck surface.

13. A concentrator deck, comprising a deck frame provided with a pair of oppositely inchned deck surfaces arranged to slope downwardly from a central ridge to form a twin deck construct-ion, riftles ext-ending diagonally over the deck surface to direct the concentrates onto said ridge and having their ends arranged in staggered relation along said ridge to direct the concentrates back and forth in a tortuous path along the ridge.

lt. A concentrator deck, comprising a deck frame provided with a pair of oppositely inclined deck surfaces arranged to slope downwardly from a central concentrate Wall to form a twin deck construction, riflies extending diagonally over the deck surface to direct the concentrates toward said wall, and outwardly flaring deflector wings secured to the opposite sides of said wall in spaced relation to the deck surface to form skimmers that direct the lighter materials away from said wall for further treatment.

15. A concentrator deck, comprising a deck frame provided with a pair of oppositely inclined deck surfaces arranged to slope downwardly from a central ridge to form a twin deck construction, a pair of feed hoppers positioned to direct the n'laterials onto the oppositely inclined deck surfaces, and a third feed hopper positioned between said pairs of hoppers and adapted to direct a different grade of materials to be treated onto the ridge portion of said deck.

16. A concentrator deck, comprising a deck frame provided with a pair of oppositely inclined deck surfaces arranged to slope downwardly from a central ridge to form a twin deck construction, means for forcing air upwardly through the deck surfaces, a pair of feed hoppers positioned to direct the materials onto the oppositely inclined deck sur faces, a third feed hopper positioned between said pair of hoppers and adapted to direct materials to be treated onto the ridge portion of the deck, and means for subjecting the materials delivered to the deck by one of said hoppers to stronger air currents than the materials delivered to the deck by the other hoppers.

17. A concentrator deck, comprising a deck frame having a material supporting deck surface, means built into the deck frame for supporting the deck surface at a transverse inclination the pitch of which gradually increases from the material receiving end of the deck toward the discharge end thereof, and riflles extending diagonally across the deck surface toward the upper side thereof and adapted to direct the concentrates towards the upper side of the deck along paths that are stepper near the discharge end of the deck than the corresponding paths near.

the material receiving end of the deck.

In testimony whereof, I have signed my name to this specification.

ALBERT H. STEBBINS. 

